archipelagoAn archipelago is a group or chain of islands clustered together in a sea or ocean.

atollAn atoll is a ring (or partial ring) of coral that forms an island in an ocean or sea. The coral sits atop a submerged volcanic cone.

bayA bay is a body of water that is partly enclosed by land (and is usually smaller than a gulf).

butteA butte is a flat-topped rock or hill formation with steep sides.

canyonA canyon is a deep valley with very steep sides - often carved from the Earth by a river.

capeA cape is a pointed piece of land that sticks out into a sea, ocean, lake, or river.

caveA cave is a large hole in the ground or in the side of a hill or mountain.

cayA cay is a low-lying sandy island formed atop a reef.

channelA channel is a body of water that connects two larger bodies of water (like the English Channel). A channel is also a part of a river or harbor that is deep enough to let ships sail through.

cliffA cliff is a steep face of rock and soil.

colA mountain pass.

continentThe land mass on Earth is divided into continents. The seven current continents are Africa, Antarctica, Asia, Australia, Europe, North America, and South America.

coveA cove is small, horseshoe-shaped body of water along the coast; the water is surrounded by land formed of soft rock.

deltaA delta is a low, watery land formed at the mouth of a river. It is formed from the silt, sand and small rocks that flow downstream in the river and are deposited in the delta. A delta is often (but not always) shaped like a triangle (hence its name, delta, a Greek letter that is shaped like a triangle).

duneA dune is a hill or a ridge made of sand. Dunes are shaped by the wind, and change all the time.

equatorThe equator is an imaginary circle around the earth, halfway between the north and south poles.

estuaryAn estuary is where a river meets the sea or ocean.

fjordA fjord is a long, narrow sea inlet that is bordered by steep cliffs.

geomorphologyGeomorphology is the scientific field that investigates how landforms are formed on the Earth (and other planets).

geyserA geyser is a natural hot spring that occasionally sprays water and steam above the ground.

glacierA glacier is a long-lasting, slowly-moving river of ice on land.

gulfA gulf is a part of the ocean (or sea) that is partly surrounded by land (it is usually larger than a bay).

hillA hill is a raised area or mound of land.

islandAn island is a piece of land that is surrounded by water.

isthmusAn isthmus is a narrow strip of land connecting two larger landmasses. An isthmus has water on two sides.

keyA key is a low-lying island (especially in the Caribbean Sea), usually formed by a reef.

lagoonA lagoon is a shallow body of water that is located alongside a coast.

lakeA lake is a large body of water surrounded by land on all sides. Really huge lakes are often called seas.

latitudeLatitude is the angular distance north or south from the equator to a particular location. The equator has a latitude of zero degrees. The North Pole has a latitude of 90 degrees North; the South Pole has a latitude of 90 degrees South.

longitudeLongitude is the angular distance east or west from the north-south line that passes through Greenwich, England, to a particular location. Greenwich, England has a longitude of zero degrees. The farther east or west of Greenwich you are, the greater your longitude. Midway Islands (in the Pacific Ocean) have a longitude of 180 degrees (they are on the opposite side of the globe from Greenwich).

marshA marsh is a type of freshwater, brackish water or saltwater wetland that is found along rivers, pond, lakes and coasts. Marsh plants grow up out of the water.

mesaA mesa is a land formation with a flat area on top and steep walls - usually occurring in dry areas.

mountainA mountain is a very tall high, natural place on Earth - higher than a hill. The tallest mountain on Earth is Mt. Everest.

oceanAn ocean is a large body of salt water that surrounds a continent. Oceans cover more the two-thirds of the Earth's surface

peninsulaA peninsula is a body of land that is surrounded by water on three sides.

plainPlains are flat lands that have only small changes in elevation.

plateauA plateau is a large, flat area of land that is higher than the surrounding land.

pondA pond is a small body of water surrounded by land. A pond is smaller than a lake.

prairieA prairie is a wide, relatively flat area of land that has grasses and only a few trees.

riverA river is a large, flowing body of water that usually empties into a sea or ocean.

seaA sea is a large body of salty water that is often connected to an ocean. A sea may be partly or completely surrounded by land.

soundA sound is a wide inlet of the sea or ocean that is parallel to the coastline; it often separates a coastline from a nearby island.

sourceA source is the beginning of a river.

straitA strait is a narrow body of water that connects two larger bodies of water.

surface runoffSurface runoff is water flow on the land that occurs when the soil is saturated with water and the excess water (from precipitation or snowmelt) runs over the surface.

swampA swamp is a type of freshwater wetland that has spongy, muddly land and a lot of water. Many trees and shrubs grow in swamps.

tributaryA tributary is a stream or river that flows into a larger river.

volcanoA volcano is a mountainous vent in the Earth's crust. When a volcano erupts, it spews out lava, ashes, and hot gases from deep inside the Earth.

waterfallWhen a river falls off steeply, there is a waterfall.

wetlandA wetland is an area of land that is often wet; the soil in wetlands are often low in oxygen. Wetland plants are adapted to life in wet soil. There are many types of wetlands, including: swamp, slough, fen, bog, marsh, moor, muskeg, peatland, bottomland, delmarva, mire, wet meadow, riparian, etc.